Introduction to Evolution and Genetics Flashcards
What creates variation in a population
mutation, recombination and gene flow
What processes influence variation in a population
selection and genetic drift
Who was the first to advocate for evolution
Jean-Baptiste de Lamarck
What was Lamarck’s theory of evolution
Lowly forms of life arise spontaneously from inanimate matter
They progress towards greater complexity
Environment alters the needs of the organisms
Use and disuse alter morphology
This is transmitted to the next generation
What were Darwin’s main ideas
All organisms have descended with modification from a common ancestor
the chief agents of modification is natural selection on individual variation
What did Darwin study to develop his theory
Fossil record Geographic distribution of species Comparative anatomy Embryology Studies on domestic animals
What were the initial problems with Natural Selection?
Peeps were ready to accept biological evolution, but thought the struggle for existence was at the species level, not the individual
Popular misconceptions about evolution
There is no “higher goal”
No progress from “lower” to “higher” life forms
Natural selection acts at individual level
Evolution and natural selection are amoral
The “law” of natural selection cannot be used to justify the class struggle, capitalism, etc
What was the blending problem for natural selection
How can traits values segregate and not merge to a mean value with no variation?
Mixing paints on a paint pallet
Who solved the blending problem but introduced another
Gregor Mendel in 1900
Heritable traits were thought to be discontinuous
What is the modern synthesis of evolution
Populations contain genetic variation that arises spontaneous and at random
This variation is subject to random fluctuations
Natural selection favours certain variants that increase fitness
Genetic variation can be exchanged between populations (gene flow) and occasionally between species
Recombination shuffles variation and generates new genotypes
Over time, genetic changes accumulate so that populations become reproductively isolated
How does biodiversity and genetic complexity increase?
Duplication and divergence
Symbiosis
Epigenesis
How does duplication and divergence increase biodiversity and genetic complexity
Duplication does not increase genetic information but it does give substrate for selection and drift leading to divergence
How does symbiosis increase biodiversity and genetic complexity
Origin of eukaryotic life, but also evolution of chromosomes (linking genes), associations between plants and fungi, animals and algae
How does epigenesis increase biodiversity and genetic complexity
Heritable changes in gene expression or cellular phenotype not due to changes in the DNA
What is Kumura Neutral Theory
Most intraspecific variability at the molecular level is neutral and variation in maintained by the input of new mutations balanced by the loss due to drift
Few DNA polymorphisms in a species are due to positive or balancing selection
What is the process of epigenetic regulation
Not all adaptive evolution occurs through mutations and changes in the DNA code
Heritable changes occur in gene expression
Modifications are DNA methylation and histone modification
Changes may remain through cell divisions and across generations (i.e. heritable)
Lamarck!`
How much needs to die to be class as a mass extinction
75% taxa
What is the current extinction rate?
Estimated 1000-fold increase over ‘background extinction rate (not yet 75%)
What has been affected by the sixth extinction
extinction of megafauna in the late Pleistocene, but currently most taxa
What is the cause of the sixth extinction
human population size expansion, loss and fragmentation of habitat, pollution, over exploitation, climate change
How do we slow the extinction rate on a global scale
Reducing pollution and greenhouse gas emission and protection of the ozone layer
How do we slow the extinction rate on a local scale
Protecting habitat, life-style changes (food, recycling etc.)
How do we slow the extinction rate on a species level
Protecting species in situ
Ex situ conservation in zoos
Reintroduce animals (plants) when habitat is restored and safe
What are the risks of captive breeding
Inbreeding depression Loss of genetic variation Outbreeding depression (hybridisation) Adaptation to captive environment Accumulation of new deleterious mutations
How to minimise the risks of captive breed
breeding with wild individuals
be aware of local adaptations
maximise migration regime?
purging regime = removing deleterious mutations through inbreeding
What is the main concern over captive population size
Too large, you get too much adaptation to captivity, too small and there is too much inbreeding depression
When doing breeding experiments, why would you limit the amount of offspring, from each individual
By equalising the reproductive ability of everyone you reduce the effects of selection
Why does deleterious alleles arise in captivity
inbreeding and all ill animals get medicine
What were the main conclusions of Oosterhout et al 2007
During reintroduction
Many fish died from parasites (epidemics)
Inbreeding Regime - lowest survival
Outbred guppies from the largest natural population - had the highest survival
Why did parasites cause such high mortality in guppies
Medication was used in captivity
Individuals were not pre-exposed to parasites before release
what animals are extinct in the wild?
Th Gaum rail and the Californian condor
Story of the Guam rail
Guam rail, a small, flightless bird, was nearly driven to extinction by the invasive brown tree snake, which was accidentally brought to the island by the U.S. military. The rails now live only in captive environments, including the National Aviary in Pittsburgh.
Story of the californian condor
In 1987, the 27 California condors left in the world were taken into captivity, making them extinct in the wild. in California zoo
retention of genetic variation in captive breeding programs can be maximized by:
maximizing the initial genetic variation by using adequate numbers of founders
minimizing the number of generations in captivity by seed storage in plants, cryopreservation or breeding from older animals
maximizing population size
maximizing N e / N .
Define ex situ conservation
“off-site conservation”, protecting organisms outside there natural habitat, often in zoos or botanical gardens
What are the IUCN goals for conservation programmes
establishing populations in secure ex situ locations educating and engaging the public on conservation issues
providing a focus for fund-raising efforts for conservation
providing animals for research on the basic biology of species, knowledge that can then be applied to conservation of species in the wild
providing animals for reintroduction programs, where applicable.
what are the 6 stages of captive breeding and reintroduction
Recognizing decline of the wild population and its genetic consequences
Founding one or more captive populations
Expanding the captive populations to a secure size Managing the captive population over generations Choosing individuals for reintroduction
Managing the reintroduced population (probably fragmented) in the wild.
